Consolidated Balance Sheets (Parenthetical) - USD ($) $ in Thousands	Dec. 31, 2020	Dec. 31, 2019
Statement Of Financial Position [Abstract]
Related party, receivable from collaboration partners	$ 943	$ 0
Related party, deferred revenue - current	67,571	0
Related party, deferred revenue - noncurrent	117,808	0
Related party, other long-term liabilities	$ 9,703	$ 0
Preferred stock, par value	$ 0.0001	$ 0.0001
Preferred stock, shares authorized	10,000,000	10,000,000
Preferred stock, shares issued	0	0
Preferred stock, shares outstanding	0	0
Common stock, par value	$ 0.0001	$ 0.0001
Common stock, shares authorized	400,000,000	400,000,000
Common stock, shares issued	65,114,685	45,925,004
Common stock, shares outstanding	65,114,685	45,925,004